Throttle Body Sizing

[Edward C. Hernandez]

Michael D. Porter commented on the throttle body sizing formula:

> To further this thought, shouldn't the intake valves duration somehow >be included in this(calculation for throttle body sizing)?

It is: that's why he includes volumetric efficiency(VE) in his formula.
Problem is, without a dyno, you have to guess your V.E.

>Who cares? Isn't the object to get as much velocity as possible?

No, the object is minimize flow restrictions while optimising the
opening rate. You are right: it is difficult to drive cars with big
throttle bodies because at low throttle settings, a few degrees makes a
huge difference in flow. OEMs get around this by designing cams into the
throttle linkage to modify the opening rate at lower throttle settings.

-- 
Ed Hernandez
Ford Motor Company
ehernan3 at ed8719.pto.ford.com